/*
 * Copyright © 2011-2013 Martin Pieuchot <mpi@openbsd.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <sys/time.h>
#include <sys/types.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <dev/usb/usb.h>

#include "libusb.h"
#include "libusbi.h"

struct device_priv {
    char *devname;                /* name of the ugen(4) node */
    int fd;                    /* device file descriptor */

    unsigned char *cdesc;            /* active config descriptor */
    usb_device_descriptor_t ddesc;        /* usb device descriptor */
};

struct handle_priv {
    int pipe[2];                /* for event notification */
    int endpoints[USB_MAX_ENDPOINTS];
};

/*
 * Backend functions
 */
static int obsd_get_device_list(struct libusb_context *,
    struct discovered_devs **);
static int obsd_open(struct libusb_device_handle *);
static void obsd_close(struct libusb_device_handle *);

static int obsd_get_device_descriptor(struct libusb_device *, unsigned char *,
    int *);
static int obsd_get_active_config_descriptor(struct libusb_device *,
    unsigned char *, size_t, int *);
static int obsd_get_config_descriptor(struct libusb_device *, uint8_t,
    unsigned char *, size_t, int *);

static int obsd_get_configuration(struct libusb_device_handle *, int *);
static int obsd_set_configuration(struct libusb_device_handle *, int);

static int obsd_claim_interface(struct libusb_device_handle *, int);
static int obsd_release_interface(struct libusb_device_handle *, int);

static int obsd_set_interface_altsetting(struct libusb_device_handle *, int,
    int);
static int obsd_clear_halt(struct libusb_device_handle *, unsigned char);
static int obsd_reset_device(struct libusb_device_handle *);
static void obsd_destroy_device(struct libusb_device *);

static int obsd_submit_transfer(struct usbi_transfer *);
static int obsd_cancel_transfer(struct usbi_transfer *);
static void obsd_clear_transfer_priv(struct usbi_transfer *);
static int obsd_handle_events(struct libusb_context *ctx, struct pollfd *,
    nfds_t, int);
static int obsd_clock_gettime(int, struct timespec *);

/*
 * Private functions
 */
static int _errno_to_libusb(int);
static int _cache_active_config_descriptor(struct libusb_device *);
static int _sync_control_transfer(struct usbi_transfer *);
static int _sync_gen_transfer(struct usbi_transfer *);
static int _access_endpoint(struct libusb_transfer *);

static int _bus_open(int);

const struct usbi_os_backend openbsd_backend = {
    "Synchronous OpenBSD backend",
    0,
    NULL,                /* init() */
    NULL,                /* exit() */
    obsd_get_device_list,
    NULL,                /* hotplug_poll */
    obsd_open,
    obsd_close,

    obsd_get_device_descriptor,
    obsd_get_active_config_descriptor,
    obsd_get_config_descriptor,
    NULL,                /* get_config_descriptor_by_value() */

    obsd_get_configuration,
    obsd_set_configuration,

    obsd_claim_interface,
    obsd_release_interface,

    obsd_set_interface_altsetting,
    obsd_clear_halt,
    obsd_reset_device,

    NULL,                /* kernel_driver_active() */
    NULL,                /* detach_kernel_driver() */
    NULL,                /* attach_kernel_driver() */

    obsd_destroy_device,

    obsd_submit_transfer,
    obsd_cancel_transfer,
    obsd_clear_transfer_priv,

    obsd_handle_events,

    obsd_clock_gettime,
    sizeof(struct device_priv),
    sizeof(struct handle_priv),
    0,                /* transfer_priv_size */
    0,                /* add_iso_packet_size */
};

#define DEVPATH    "/dev/"
#define USBDEV    DEVPATH "usb"

int
obsd_get_device_list(struct libusb_context * ctx,
    struct discovered_devs **discdevs)
{
    struct discovered_devs *ddd;
    struct libusb_device *dev;
    struct device_priv *dpriv;
    struct usb_device_info di;
    struct usb_device_ddesc dd;
    unsigned long session_id;
    char devices[USB_MAX_DEVICES];
    char busnode[16];
    char *udevname;
    int fd, addr, i, j;

    usbi_dbg("");

    for (i = 0; i < 8; i++) {
        snprintf(busnode, sizeof(busnode), USBDEV "%d", i);

        if ((fd = open(busnode, O_RDWR)) < 0) {
            if (errno != ENOENT && errno != ENXIO)
                usbi_err(ctx, "could not open %s", busnode);
            continue;
        }

        bzero(devices, sizeof(devices));
        for (addr = 1; addr < USB_MAX_DEVICES; addr++) {
            if (devices[addr])
                continue;

            di.udi_addr = addr;
            if (ioctl(fd, USB_DEVICEINFO, &di) < 0)
                continue;

            /*
             * XXX If ugen(4) is attached to the USB device
             * it will be used.
             */
            udevname = NULL;
            for (j = 0; j < USB_MAX_DEVNAMES; j++)
                if (!strncmp("ugen", di.udi_devnames[j], 4)) {
                    udevname = strdup(di.udi_devnames[j]);
                    break;
                }

            session_id = (di.udi_bus << 8 | di.udi_addr);
            dev = usbi_get_device_by_session_id(ctx, session_id);

            if (dev == NULL) {
                dev = usbi_alloc_device(ctx, session_id);
                if (dev == NULL) {
                    close(fd);
                    return (LIBUSB_ERROR_NO_MEM);
                }

                dev->bus_number = di.udi_bus;
                dev->device_address = di.udi_addr;
                dev->speed = di.udi_speed;

                dpriv = (struct device_priv *)dev->os_priv;
                dpriv->fd = -1;
                dpriv->cdesc = NULL;
                dpriv->devname = udevname;

                dd.udd_bus = di.udi_bus;
                dd.udd_addr = di.udi_addr;
                if (ioctl(fd, USB_DEVICE_GET_DDESC, &dd) < 0) {
                    libusb_unref_device(dev);
                    continue;
                }
                dpriv->ddesc = dd.udd_desc;

                if (_cache_active_config_descriptor(dev)) {
                    libusb_unref_device(dev);
                    continue;
                }

                if (usbi_sanitize_device(dev)) {
                    libusb_unref_device(dev);
                    continue;
                }
            }

            ddd = discovered_devs_append(*discdevs, dev);
            if (ddd == NULL) {
                close(fd);
                return (LIBUSB_ERROR_NO_MEM);
            }
            libusb_unref_device(dev);

            *discdevs = ddd;
            devices[addr] = 1;
        }

        close(fd);
    }

    return (LIBUSB_SUCCESS);
}

int
obsd_open(struct libusb_device_handle *handle)
{
    struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
    struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
    char devnode[16];

    if (dpriv->devname) {
        /*
         * Only open ugen(4) attached devices read-write, all
         * read-only operations are done through the bus node.
         */
        snprintf(devnode, sizeof(devnode), DEVPATH "%s.00",
            dpriv->devname);
        dpriv->fd = open(devnode, O_RDWR);
        if (dpriv->fd < 0)
            return _errno_to_libusb(errno);

        usbi_dbg("open %s: fd %d", devnode, dpriv->fd);
    }

    if (pipe(hpriv->pipe) < 0)
        return _errno_to_libusb(errno);

    return usbi_add_pollfd(HANDLE_CTX(handle), hpriv->pipe[0], POLLIN);
}

void
obsd_close(struct libusb_device_handle *handle)
{
    struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
    struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;

    if (dpriv->devname) {
        usbi_dbg("close: fd %d", dpriv->fd);

        close(dpriv->fd);
        dpriv->fd = -1;
    }

    usbi_remove_pollfd(HANDLE_CTX(handle), hpriv->pipe[0]);

    close(hpriv->pipe[0]);
    close(hpriv->pipe[1]);
}

int
obsd_get_device_descriptor(struct libusb_device *dev, unsigned char *buf,
    int *host_endian)
{
    struct device_priv *dpriv = (struct device_priv *)dev->os_priv;

    usbi_dbg("");

    memcpy(buf, &dpriv->ddesc, DEVICE_DESC_LENGTH);

    *host_endian = 0;

    return (LIBUSB_SUCCESS);
}

int
obsd_get_active_config_descriptor(struct libusb_device *dev,
    unsigned char *buf, size_t len, int *host_endian)
{
    struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
    usb_config_descriptor_t *ucd = (usb_config_descriptor_t *)dpriv->cdesc;

    len = MIN(len, UGETW(ucd->wTotalLength));

    usbi_dbg("len %d", len);

    memcpy(buf, dpriv->cdesc, len);

    *host_endian = 0;

    return (len);
}

int
obsd_get_config_descriptor(struct libusb_device *dev, uint8_t idx,
    unsigned char *buf, size_t len, int *host_endian)
{
    struct usb_device_fdesc udf;
    int fd, err;

    if ((fd = _bus_open(dev->bus_number)) < 0)
        return _errno_to_libusb(errno);

    udf.udf_bus = dev->bus_number;
    udf.udf_addr = dev->device_address;
    udf.udf_config_index = idx;
    udf.udf_size = len;
    udf.udf_data = buf;

    usbi_dbg("index %d, len %d", udf.udf_config_index, len);

    if (ioctl(fd, USB_DEVICE_GET_FDESC, &udf) < 0) {
        err = errno;
        close(fd);
        return _errno_to_libusb(err);
    }
    close(fd);

    *host_endian = 0;

    return (len);
}

int
obsd_get_configuration(struct libusb_device_handle *handle, int *config)
{
    struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
    usb_config_descriptor_t *ucd = (usb_config_descriptor_t *)dpriv->cdesc;

    *config = ucd->bConfigurationValue;

    usbi_dbg("bConfigurationValue %d", *config);

    return (LIBUSB_SUCCESS);
}

int
obsd_set_configuration(struct libusb_device_handle *handle, int config)
{
    struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;

    if (dpriv->devname == NULL)
        return (LIBUSB_ERROR_NOT_SUPPORTED);

    usbi_dbg("bConfigurationValue %d", config);

    if (ioctl(dpriv->fd, USB_SET_CONFIG, &config) < 0)
        return _errno_to_libusb(errno);

    return _cache_active_config_descriptor(handle->dev);
}

int
obsd_claim_interface(struct libusb_device_handle *handle, int iface)
{
    struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
    int i;

    for (i = 0; i < USB_MAX_ENDPOINTS; i++)
        hpriv->endpoints[i] = -1;

    return (LIBUSB_SUCCESS);
}

int
obsd_release_interface(struct libusb_device_handle *handle, int iface)
{
    struct handle_priv *hpriv = (struct handle_priv *)handle->os_priv;
    int i;

    for (i = 0; i < USB_MAX_ENDPOINTS; i++)
        if (hpriv->endpoints[i] >= 0)
            close(hpriv->endpoints[i]);

    return (LIBUSB_SUCCESS);
}

int
obsd_set_interface_altsetting(struct libusb_device_handle *handle, int iface,
    int altsetting)
{
    struct device_priv *dpriv = (struct device_priv *)handle->dev->os_priv;
    struct usb_alt_interface intf;

    if (dpriv->devname == NULL)
        return (LIBUSB_ERROR_NOT_SUPPORTED);

    usbi_dbg("iface %d, setting %d", iface, altsetting);

    memset(&intf, 0, sizeof(intf));

    intf.uai_interface_index = iface;
    intf.uai_alt_no = altsetting;

    if (ioctl(dpriv->fd, USB_SET_ALTINTERFACE, &intf) < 0)
        return _errno_to_libusb(errno);

    return (LIBUSB_SUCCESS);
}

int
obsd_clear_halt(struct libusb_device_handle *handle, unsigned char endpoint)
{
    struct usb_ctl_request req;
    int fd, err;

    if ((fd = _bus_open(handle->dev->bus_number)) < 0)
        return _errno_to_libusb(errno);

    usbi_dbg("");

    req.ucr_addr = handle->dev->device_address;
    req.ucr_request.bmRequestType = UT_WRITE_ENDPOINT;
    req.ucr_request.bRequest = UR_CLEAR_FEATURE;
    USETW(req.ucr_request.wValue, UF_ENDPOINT_HALT);
    USETW(req.ucr_request.wIndex, endpoint);
    USETW(req.ucr_request.wLength, 0);

    if (ioctl(fd, USB_REQUEST, &req) < 0) {
        err = errno;
        close(fd);
        return _errno_to_libusb(err);
    }
    close(fd);

    return (LIBUSB_SUCCESS);
}

int
obsd_reset_device(struct libusb_device_handle *handle)
{
    usbi_dbg("");

    return (LIBUSB_ERROR_NOT_SUPPORTED);
}

void
obsd_destroy_device(struct libusb_device *dev)
{
    struct device_priv *dpriv = (struct device_priv *)dev->os_priv;

    usbi_dbg("");

    free(dpriv->cdesc);
    free(dpriv->devname);
}

int
obsd_submit_transfer(struct usbi_transfer *itransfer)
{
    struct libusb_transfer *transfer;
    struct handle_priv *hpriv;
    int err = 0;

    usbi_dbg("");

    transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
    hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;

    switch (transfer->type) {
    case LIBUSB_TRANSFER_TYPE_CONTROL:
        err = _sync_control_transfer(itransfer);
        break;
    case LIBUSB_TRANSFER_TYPE_ISOCHRONOUS:
        if (IS_XFEROUT(transfer)) {
            /* Isochronous write is not supported */
            err = LIBUSB_ERROR_NOT_SUPPORTED;
            break;
        }
        err = _sync_gen_transfer(itransfer);
        break;
    case LIBUSB_TRANSFER_TYPE_BULK:
    case LIBUSB_TRANSFER_TYPE_INTERRUPT:
        if (IS_XFEROUT(transfer) &&
            transfer->flags & LIBUSB_TRANSFER_ADD_ZERO_PACKET) {
            err = LIBUSB_ERROR_NOT_SUPPORTED;
            break;
        }
        err = _sync_gen_transfer(itransfer);
        break;
    }

    if (err)
        return (err);

    if (write(hpriv->pipe[1], &itransfer, sizeof(itransfer)) < 0)
        return _errno_to_libusb(errno);

    return (LIBUSB_SUCCESS);
}

int
obsd_cancel_transfer(struct usbi_transfer *itransfer)
{
    usbi_dbg("");

    return (LIBUSB_ERROR_NOT_SUPPORTED);
}

void
obsd_clear_transfer_priv(struct usbi_transfer *itransfer)
{
    usbi_dbg("");

    /* Nothing to do */
}

int
obsd_handle_events(struct libusb_context *ctx, struct pollfd *fds, nfds_t nfds,
    int num_ready)
{
    struct libusb_device_handle *handle;
    struct handle_priv *hpriv = NULL;
    struct usbi_transfer *itransfer;
    struct pollfd *pollfd;
    int i, err = 0;

    usbi_dbg("");

    pthread_mutex_lock(&ctx->open_devs_lock);
    for (i = 0; i < nfds && num_ready > 0; i++) {
        pollfd = &fds[i];

        if (!pollfd->revents)
            continue;

        hpriv = NULL;
        num_ready--;
        list_for_each_entry(handle, &ctx->open_devs, list,
            struct libusb_device_handle) {
            hpriv = (struct handle_priv *)handle->os_priv;

            if (hpriv->pipe[0] == pollfd->fd)
                break;

            hpriv = NULL;
        }

        if (NULL == hpriv) {
            usbi_dbg("fd %d is not an event pipe!", pollfd->fd);
            err = ENOENT;
            break;
        }

        if (pollfd->revents & POLLERR) {
            usbi_remove_pollfd(HANDLE_CTX(handle), hpriv->pipe[0]);
            usbi_handle_disconnect(handle);
            continue;
        }

        if (read(hpriv->pipe[0], &itransfer, sizeof(itransfer)) < 0) {
            err = errno;
            break;
        }

        if ((err = usbi_handle_transfer_completion(itransfer,
            LIBUSB_TRANSFER_COMPLETED)))
            break;
    }
    pthread_mutex_unlock(&ctx->open_devs_lock);

    if (err)
        return _errno_to_libusb(err);

    return (LIBUSB_SUCCESS);
}

int
obsd_clock_gettime(int clkid, struct timespec *tp)
{
    usbi_dbg("clock %d", clkid);

    if (clkid == USBI_CLOCK_REALTIME)
        return clock_gettime(CLOCK_REALTIME, tp);

    if (clkid == USBI_CLOCK_MONOTONIC)
        return clock_gettime(CLOCK_MONOTONIC, tp);

    return (LIBUSB_ERROR_INVALID_PARAM);
}

int
_errno_to_libusb(int err)
{
    usbi_dbg("error: %s (%d)", strerror(err), err);

    switch (err) {
    case EIO:
        return (LIBUSB_ERROR_IO);
    case EACCES:
        return (LIBUSB_ERROR_ACCESS);
    case ENOENT:
        return (LIBUSB_ERROR_NO_DEVICE);
    case ENOMEM:
        return (LIBUSB_ERROR_NO_MEM);
    case ETIMEDOUT:
        return (LIBUSB_ERROR_TIMEOUT);
    }

    return (LIBUSB_ERROR_OTHER);
}

int
_cache_active_config_descriptor(struct libusb_device *dev)
{
    struct device_priv *dpriv = (struct device_priv *)dev->os_priv;
    struct usb_device_cdesc udc;
    struct usb_device_fdesc udf;
    unsigned char* buf;
    int fd, len, err;

    if ((fd = _bus_open(dev->bus_number)) < 0)
        return _errno_to_libusb(errno);

    usbi_dbg("fd %d, addr %d", fd, dev->device_address);

    udc.udc_bus = dev->bus_number;
    udc.udc_addr = dev->device_address;
    udc.udc_config_index = USB_CURRENT_CONFIG_INDEX;
    if (ioctl(fd, USB_DEVICE_GET_CDESC, &udc) < 0) {
        err = errno;
        close(fd);
        return _errno_to_libusb(errno);
    }

    usbi_dbg("active bLength %d", udc.udc_desc.bLength);

    len = UGETW(udc.udc_desc.wTotalLength);
    buf = malloc(len);
    if (buf == NULL)
        return (LIBUSB_ERROR_NO_MEM);

    udf.udf_bus = dev->bus_number;
    udf.udf_addr = dev->device_address;
    udf.udf_config_index = udc.udc_config_index;
    udf.udf_size = len;
    udf.udf_data = buf;

    usbi_dbg("index %d, len %d", udf.udf_config_index, len);

    if (ioctl(fd, USB_DEVICE_GET_FDESC, &udf) < 0) {
        err = errno;
        close(fd);
        free(buf);
        return _errno_to_libusb(err);
    }
    close(fd);

    if (dpriv->cdesc)
        free(dpriv->cdesc);
    dpriv->cdesc = buf;

    return (LIBUSB_SUCCESS);
}

int
_sync_control_transfer(struct usbi_transfer *itransfer)
{
    struct libusb_transfer *transfer;
    struct libusb_control_setup *setup;
    struct device_priv *dpriv;
    struct usb_ctl_request req;

    transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
    dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;
    setup = (struct libusb_control_setup *)transfer->buffer;

    usbi_dbg("type %x request %x value %x index %d length %d timeout %d",
        setup->bmRequestType, setup->bRequest,
        libusb_le16_to_cpu(setup->wValue),
        libusb_le16_to_cpu(setup->wIndex),
        libusb_le16_to_cpu(setup->wLength), transfer->timeout);

    req.ucr_addr = transfer->dev_handle->dev->device_address;
    req.ucr_request.bmRequestType = setup->bmRequestType;
    req.ucr_request.bRequest = setup->bRequest;
    /* Don't use USETW, libusb already deals with the endianness */
    (*(uint16_t *)req.ucr_request.wValue) = setup->wValue;
    (*(uint16_t *)req.ucr_request.wIndex) = setup->wIndex;
    (*(uint16_t *)req.ucr_request.wLength) = setup->wLength;
    req.ucr_data = transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE;

    if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
        req.ucr_flags = USBD_SHORT_XFER_OK;

    if (dpriv->devname == NULL) {
        /*
         * XXX If the device is not attached to ugen(4) it is
         * XXX still possible to submit a control transfer but
         * XXX with the default timeout only.
         */
        int fd, err;

        if ((fd = _bus_open(transfer->dev_handle->dev->bus_number)) < 0)
            return _errno_to_libusb(errno);

        if ((ioctl(fd, USB_REQUEST, &req)) < 0) {
            err = errno;
            close(fd);
            return _errno_to_libusb(err);
        }
        close(fd);
    } else {
        if ((ioctl(dpriv->fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
            return _errno_to_libusb(errno);

        if ((ioctl(dpriv->fd, USB_DO_REQUEST, &req)) < 0)
            return _errno_to_libusb(errno);
    }

    itransfer->transferred = req.ucr_actlen;

    usbi_dbg("transferred %d", itransfer->transferred);

    return (0);
}

int
_access_endpoint(struct libusb_transfer *transfer)
{
    struct handle_priv *hpriv;
    struct device_priv *dpriv;
    char devnode[16];
    int fd, endpt;
    mode_t mode;

    hpriv = (struct handle_priv *)transfer->dev_handle->os_priv;
    dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;

    endpt = UE_GET_ADDR(transfer->endpoint);
    mode = IS_XFERIN(transfer) ? O_RDONLY : O_WRONLY;

    usbi_dbg("endpoint %d mode %d", endpt, mode);

    if (hpriv->endpoints[endpt] < 0) {
        /* Pick the right endpoint node */
        snprintf(devnode, sizeof(devnode), DEVPATH "%s.%02d",
            dpriv->devname, endpt);

        /* We may need to read/write to the same endpoint later. */
        if (((fd = open(devnode, O_RDWR)) < 0) && (errno == ENXIO))
            if ((fd = open(devnode, mode)) < 0)
                return (-1);

        hpriv->endpoints[endpt] = fd;
    }

    return (hpriv->endpoints[endpt]);
}

int
_sync_gen_transfer(struct usbi_transfer *itransfer)
{
    struct libusb_transfer *transfer;
    struct device_priv *dpriv;
    int fd, nr = 1;

    transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
    dpriv = (struct device_priv *)transfer->dev_handle->dev->os_priv;

    if (dpriv->devname == NULL)
        return (LIBUSB_ERROR_NOT_SUPPORTED);

    /*
     * Bulk, Interrupt or Isochronous transfer depends on the
     * endpoint and thus the node to open.
     */
    if ((fd = _access_endpoint(transfer)) < 0)
        return _errno_to_libusb(errno);

    if ((ioctl(fd, USB_SET_TIMEOUT, &transfer->timeout)) < 0)
        return _errno_to_libusb(errno);

    if (IS_XFERIN(transfer)) {
        if ((transfer->flags & LIBUSB_TRANSFER_SHORT_NOT_OK) == 0)
            if ((ioctl(fd, USB_SET_SHORT_XFER, &nr)) < 0)
                return _errno_to_libusb(errno);

        nr = read(fd, transfer->buffer, transfer->length);
    } else {
        nr = write(fd, transfer->buffer, transfer->length);
    }

    if (nr < 0)
        return _errno_to_libusb(errno);

    itransfer->transferred = nr;

    return (0);
}

int
_bus_open(int number)
{
    char busnode[16];

    snprintf(busnode, sizeof(busnode), USBDEV "%d", number);

    return open(busnode, O_RDWR);
}

